The present invention relates to a partition member of a liquid filled vibration isolating device used for supporting a vibration generating body such as an automobile engine.
In general, a vibration generating body such as an automobile engine is supported by a vibration isolating device in order to control vibration transmission from a vibration generating body to a vehicle body. One prior art example is shown in FIG. 6. The vibration isolating device shown in FIG. 6 comprises an outer cylindrical metal fitting 101 secured to a vehicle body, a boss metal fitting 102 secured to an engine, a vibration isolating base body 103 formed of a rubber elastic body interposed between the outer cylindrical metal fitting 101 and the boss metal fitting 102 so as to damp vibration of higher frequency, and a liquid chamber 104 wherein liquid is enclosed.
The liquid chamber 104 is divided into a main liquid chamber 108 and an auxiliary liquid chamber 109 by a partition member 107 formed by a ring-shaped metal fitting 105 and a rubber elastic membrane 106 closing an opening of the metal fitting 105. The main liquid chamber 108 and the auxiliary liquid chamber 109 are communicated with each other by an orifice provided at a peripheral portion of the ring-shaped metal fitting 105. A liquid flow between the main liquid chamber 108 and the auxiliary liquid chamber 109 damps vibration of lower frequency.
A partition member is made of an aluminum casting or synthetic resin casting or constituted by bonding two superimposed metal plates with each other by means of spot-welding. However, since the partition member is provided with an orifice groove opened outwards and an orifice opening at the peripheral portion thereof, a mold construction becomes complicated and in addition secondary working such as trimming work after molding is indispensable. On the other hand, a partition member formed by integrally bonding two metal plates is easily formed by press molding and requires no complicated mold as a molded member. However, it has a drawback in that a bonding process, such as spot-welding, is required.
Further in the case of a partition member providing with a rubber elastic membrane for damping high frequency vibration, a vulcanization adhesion process of the rubber elastic membrane is required, which results the increases in the production process and production cost. Therefore, a partition member of high productivity has been desired.
In view of the above, it is an object of the present invention to provide a partition member formed by integrally bonding two metal plates, which does not require a complicated mold and trimming work, with high productivity.
In order to attain the above object, the present invention provides a partition member of a liquid filled vibration isolating device comprising a ring-shaped metal fitting provided with an orifice groove opened outwards at an outer periphery thereof and a rubber elastic membrane closing an opening of the ring-shaped metal fitting and providing with an orifice constituted by a space surrounded by the orifice groove and an inner peripheral face of a liquid chamber. The ring-shaped metal fitting is formed by superimposing a first metal fitting in a ring shape and a second metal fitting in a ring shape in the axial direction, at least any one of the first metal fitting or the second metal fitting being bent at its outer peripheral portion so as to form the orifice groove by the outer peripheral portions of the first and second ring-shaped metal fittings. The first metal fitting, the second metal fitting and the rubber elastic membrane are bonded integrally by vulcanization adhesion of inner peripheral overlap spaces of the first and second ring-shaped metal fittings with a peripheral portion of the rubber elastic membrane.
In the partition member in accordance with the present invention, the ring-shaped metal fitting is formed by integrally bonding the axially superimposed metal fittings with the peripheral portion of the rubber elastic membrane without performing an additional bonding process such as spot welding.
In order to integrally and strongly bond the two metal fittings, it is preferable that an inner peripheral portion of the first metal fitting is bent toward the second metal fitting to form an inner rib to be embedded in the peripheral portion of the rubber elastic membrane. Namely, the contact area between the first metal fitting and the peripheral portion of the rubber elastic membrane becomes large and the peripheral portion of the rubber elastic membrane is reinforced by the inner rib so as to not be distorted easily, and thereby the two metal fittings are hardly displaced from each other in the axial direction.
Namely, the present invention also provides a partition member of a liquid filled vibration isolating device comprising a ring-shaped metal fitting provided with an orifice groove opened outwards at an outer periphery thereof and a rubber elastic membrane closing an opening of said ring-shaped metal fitting and providing with an orifice constituted by a space surrounded by the orifice groove and an inner peripheral face of a liquid chamber. The ring-shaped metal fitting is formed by superimposing a first metal fitting in a ring shape and a second metal fitting in a ring shape in the axial direction, at least any one of the first metal fitting or the second metal fitting being bent at its outer peripheral portion so as to form the orifice groove by the outer peripheral portions of the first and second ring-shaped metal fittings. An inner peripheral portion of the first metal fitting is bent toward the second metal fitting to form an inner rib. The first metal fitting, the second metal fitting and the rubber elastic membrane are bonded integrally by vulcanization adhesion of inner peripheral overlap spaces of the first and second metal fittings and the inner rib with a peripheral portion of the rubber elastic membrane.
It is also preferable that a clearance gap is formed at an intermediate portion between the peripheral portion of the rubber elastic membrane and an orifice opening of the orifice groove for preventing the orifice opening from being clogged by a rubber elastic material flowing at the time of vulcanization adhesion.
According to the present invention, since the ring-shaped metal fitting is formed by interposing two metal fittings simply processed, for example by press working and integrally bonding with the rubber elastic membrane, the productivity of the partition member is enhanced and the production equipment can be simplified, which contributes to rational and low-cost production.